The Efficient Synthesis and Anti-Fatigue Activity Evaluation of Macamides: The Unique Bioactive Compounds in Maca.

Macamides are a class of amide alkaloids that are only found in maca and are widely considered to be its bioactive marker compounds. More than thirty macamide monomers have been identified in recent years; however, it is difficult to obtain a single macamide monomer from the maca plant because of their similar structures and characteristics. We used the carbodiimide condensation method (CCM) to efficiently synthesize five typical macamides, including N-benzyl-hexadecanamide (NBH), N-benzyl-9Z,12Z,15Z-octadecenamide, N-(3-methoxybenzyl)-9Z,12Z-octadecenamide, N-benzyl-9Z,12Z-octadecenamide, and N-(3-methoxybenzyl)-9Z,12Z,15Z-octadecadienamide. All the synthesized macamides were purified by a one-step HPLC with a purity of more than 95%. NBH is the most abundant macamide monomer in natural maca, and it was selected to evaluate the anti-fatigue effects of macamides. The results indicated that NBH could enhance the endurance capacity of mice by increasing liver glycogen levels and decreasing blood urea nitrogen, lactate dehydrogenase, blood ammonia, and blood lactic acid levels. Macamides might be the active substances that give maca its anti-fatigue active function.

Identification and Characterization of Fibronectin-Binding Peptides in Gelatin.

Collagen and fibronectin (FN) are important components in the extracellular matrix (ECM). Collagen-FN binding belongs to protein-protein interaction and plays a key role in regulating cell behaviors. In this study, FN-binding peptides were isolated from gelatin (degraded collagen) using affinity chromatography, and the amino acid sequences were determined using HPLC-MS. The results indicated that all FN-binding peptides contained GPAG or GPPG. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and dual-polarization interferometry (DPI) were used to analyze the effects of hydroxylation polypeptide on FN binding activity. DPI analysis indicated that peptides with molecular weight (MW) between 2 kDa and 30 kDa showed higher FN-binding activity, indicating MW range played an important role in the interaction between FN and peptides. Finally, two peptides with similar sequences except for hydroxylation of prolines were synthesized. The FN-binding properties of the synthesized peptides were determined by MALDI-TOF MS. For peptide, GAPGADGP*AGAPGTP*GPQGIAGQR, hydroxylation of P8 and P15 is necessary for FN-binding. For peptide, GPPGPMGPPGLAGPPGESGR, the FN-binding process is independent of proline hydroxylation. Thus, FN-binding properties are proline-hydroxylation dependent.

Immobilization of native type I collagen on polypropylene fabrics as a substrate for HepG2 cell culture.

Background/aims The critical part of a bio-artificial liver device is establishment of a bioreactor filled with liver cells. However, it is still unclear how to maintain benign cell function while achieving the sufficient cell quantity. In the current study, we aim to establish a novel carrier for the culture of HepG2 cells, a liver cell line, by modifying polypropylene nonwoven fabrics with native type I collagen. Methods "Piranha" solution, KH-550 and glutaraldehyde subsequently were used to bridge native type I collagen and polypropylene nonwoven fabrics. The type I collagen-coupled polypropylene nonwoven fabric was characterized by XPS, SEM, ATR-FTIR and water contact angle measurement. Furthermore, the biocompatibility between HepG2 cells and fiber film is evaluated by the ability of cell proliferation, albumin secretion, as well as urea synthesis. Results The coating of collagen onto polypropylene fabrics was more efficient using the chemical covalent binding method than direct immersion, which was validated by the presence of collagen-related elements and chemical bond. The adding of collagen in polypropylene fabrics promoted hydrophilicity and HepG2 cell adherence. Additionally, enhanced cell proliferation, increased albumin secretion and urea synthesis were observed in HepG2 cells growing on collagen-coated polypropylene fabrics. Conclusions The collagen coated polypropylene nonwoven fabrics, acting as a feasible substrate for HepG2 cell culture, may be used as a promising liver cell carrier for artificial liver reactor.

[Collagen quantitation by detection of marker peptides with HPLC-MS].

A method for quantitation of collagen was established by detecting marker peptide with high performance liquid chromatography-mass spectrometry (HPLC-MS). Theoretical marker peptides were selected by sequence comparison. Bovine collagen type I was digested with trypsin. Marker peptides typical for collagen type I were identified with HPLC-MS. The relationship between the abundance of marker peptides and collagen concentration was established. The results show that GEAGPSGPAGPTGAR and the other 5 peptides showed high resolution during chromatographic separation and high signal intensity during MS analysis. Peptide signal intensity and collagen concentration showed a good linear relationship in the range from 0.1 to 3 mg/mL. Bovine tendon and collagen sponge were used as actual samples and collagen contents were determined as 90.2% and 93.4% respectively. Quantitation of marker peptides of collagen was a feasible method to identify and quantify collagens in medical device research and development.